From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE119C433DB for ; Mon, 25 Jan 2021 04:41:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5388922472 for ; Mon, 25 Jan 2021 04:41:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5388922472 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B9A238D0002; Sun, 24 Jan 2021 23:41:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B480D8D0001; Sun, 24 Jan 2021 23:41:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9E99B8D0002; Sun, 24 Jan 2021 23:41:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 82BFA8D0001 for ; Sun, 24 Jan 2021 23:41:17 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 4FA918249980 for ; Mon, 25 Jan 2021 04:41:17 +0000 (UTC) X-FDA: 77743048194.06.light43_220e37627582 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin06.hostedemail.com (Postfix) with ESMTP id 2798110033C50 for ; Mon, 25 Jan 2021 04:41:17 +0000 (UTC) X-HE-Tag: light43_220e37627582 X-Filterd-Recvd-Size: 5697 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Mon, 25 Jan 2021 04:41:15 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04420;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UMkZ0XA_1611549671; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0UMkZ0XA_1611549671) by smtp.aliyun-inc.com(127.0.0.1); Mon, 25 Jan 2021 12:41:13 +0800 Subject: Re: [PATCH] mm/filemap: Adding missing mem_cgroup_uncharge() to __add_to_page_cache_locked() To: Waiman Long , Andrew Morton , Johannes Weiner Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210125042441.20030-1-longman@redhat.com> From: Alex Shi Message-ID: <4fca896e-98fe-f17c-b649-1d659761f985@linux.alibaba.com> Date: Mon, 25 Jan 2021 12:41:10 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20210125042441.20030-1-longman@redhat.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Reviewed-by: Alex Shi =D4=DA 2021/1/25 =CF=C2=CE=E712:24, Waiman Long =D0=B4=B5=C0: > The commit 3fea5a499d57 ("mm: memcontrol: convert page > cache to a new mem_cgroup_charge() API") introduced a bug in > __add_to_page_cache_locked() causing the following splat: >=20 > [ 1570.068330] page dumped because: VM_BUG_ON_PAGE(page_memcg(page)) > [ 1570.068333] pages's memcg:ffff8889a4116000 > [ 1570.068343] ------------[ cut here ]------------ > [ 1570.068346] kernel BUG at mm/memcontrol.c:2924! > [ 1570.068355] invalid opcode: 0000 [#1] SMP KASAN PTI > [ 1570.068359] CPU: 35 PID: 12345 Comm: cat Tainted: G S W I = 5.11.0-rc4-debug+ #1 > [ 1570.068363] Hardware name: HP HP Z8 G4 Workstation/81C7, BIOS P60 v= 01.25 12/06/2017 > [ 1570.068365] RIP: 0010:commit_charge+0xf4/0x130 > : > [ 1570.068375] RSP: 0018:ffff8881b38d70e8 EFLAGS: 00010286 > [ 1570.068379] RAX: 0000000000000000 RBX: ffffea00260ddd00 RCX: 000000= 0000000027 > [ 1570.068382] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88= 907ebe05a8 > [ 1570.068384] RBP: ffffea00260ddd00 R08: ffffed120fd7c0b6 R09: ffffed= 120fd7c0b6 > [ 1570.068386] R10: ffff88907ebe05ab R11: ffffed120fd7c0b5 R12: ffffea= 00260ddd38 > [ 1570.068389] R13: ffff8889a4116000 R14: ffff8889a4116000 R15: 000000= 0000000001 > [ 1570.068391] FS: 00007ff039638680(0000) GS:ffff88907ea00000(0000) k= nlGS:0000000000000000 > [ 1570.068394] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 1570.068396] CR2: 00007f36f354cc20 CR3: 00000008a0126006 CR4: 000000= 00007706e0 > [ 1570.068398] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000000= 0000000000 > [ 1570.068400] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 000000= 0000000400 > [ 1570.068402] PKRU: 55555554 > [ 1570.068404] Call Trace: > [ 1570.068407] mem_cgroup_charge+0x175/0x770 > [ 1570.068413] __add_to_page_cache_locked+0x712/0xad0 > [ 1570.068439] add_to_page_cache_lru+0xc5/0x1f0 > [ 1570.068461] cachefiles_read_or_alloc_pages+0x895/0x2e10 [cachefile= s] > [ 1570.068524] __fscache_read_or_alloc_pages+0x6c0/0xa00 [fscache] > [ 1570.068540] __nfs_readpages_from_fscache+0x16d/0x630 [nfs] > [ 1570.068585] nfs_readpages+0x24e/0x540 [nfs] > [ 1570.068693] read_pages+0x5b1/0xc40 > [ 1570.068711] page_cache_ra_unbounded+0x460/0x750 > [ 1570.068729] generic_file_buffered_read_get_pages+0x290/0x1710 > [ 1570.068756] generic_file_buffered_read+0x2a9/0xc30 > [ 1570.068832] nfs_file_read+0x13f/0x230 [nfs] > [ 1570.068872] new_sync_read+0x3af/0x610 > [ 1570.068901] vfs_read+0x339/0x4b0 > [ 1570.068909] ksys_read+0xf1/0x1c0 > [ 1570.068920] do_syscall_64+0x33/0x40 > [ 1570.068926] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 1570.068930] RIP: 0033:0x7ff039135595 >=20 > Before that commit, there was a try_charge() and commit_charge() > in __add_to_page_cache_locked(). These 2 separated charge functions > were replaced by a single mem_cgroup_charge(). However, it forgot > to add a matching mem_cgroup_uncharge() when the xarray insertion > failed with the page released back to the pool. Fix this by adding a > mem_cgroup_uncharge() call when insertion error happens. >=20 > Fixes: 3fea5a499d57 ("mm: memcontrol: convert page cache to a new mem_c= group_charge() API") > Signed-off-by: Waiman Long > --- > mm/filemap.c | 4 ++++ > 1 file changed, 4 insertions(+) >=20 > diff --git a/mm/filemap.c b/mm/filemap.c > index 5c9d564317a5..aa0e0fb04670 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -835,6 +835,7 @@ noinline int __add_to_page_cache_locked(struct page= *page, > XA_STATE(xas, &mapping->i_pages, offset); > int huge =3D PageHuge(page); > int error; > + bool charged =3D false; > =20 > VM_BUG_ON_PAGE(!PageLocked(page), page); > VM_BUG_ON_PAGE(PageSwapBacked(page), page); > @@ -848,6 +849,7 @@ noinline int __add_to_page_cache_locked(struct page= *page, > error =3D mem_cgroup_charge(page, current->mm, gfp); > if (error) > goto error; > + charged =3D true; > } > =20 > gfp &=3D GFP_RECLAIM_MASK; > @@ -896,6 +898,8 @@ noinline int __add_to_page_cache_locked(struct page= *page, > =20 > if (xas_error(&xas)) { > error =3D xas_error(&xas); > + if (charged) > + mem_cgroup_uncharge(page); > goto error; > } > =20 >=20